Sound-producing device



Nova 29, 1927.

G. RAMSEY SOUND PRODUCING DEVICE Filed Dec. 21L 1925 2 Sheets-Sheet 'l OSCILL/i 7'01? RECORD INVENTOR NW, 2%,, E927. e. RAMSEY SOUND PRODUCING DEVICE 2 Sheets-Sheet 2 Filed Dec. 21, 1925 AMPz 0-751? 0/? Riff/Vii? 17/1 0/0 I Lil MA (i/VET INVENTOR Patented Nov. 2 9, 1927.

UNITED STATES PATENT OFFICE.

SOUND-PRODUCING DEVICE.

Application flled December 21, 1925. Serial No. 76,707.

The present invention relates to the production of sound and more specially to constructions adapted for the reproduction of sounds, and may be useful in connection with phonographs, radio, etc.

Heretofore in the art production of sound, and more specially reproduction by phonographs, radios, etc., the reproduced sound has been brought about by movement of diaphragms, or the like, to attempt to cause air waves to be formed which were intended to correspond to the certain sounds that were desired to be reproduced. All of these sound reproducing devices using a diaphragm dis-.

tort the sound wave because of the inertia of the diaphragm and also the tendency of the diaphragm to have certain vibratory characteristics of its own. These faults were particularly noticeable and are especially objectionable in sound reproduction when it is. desired to accurately reproduce sounds which originate from the human voice, musical instruments, or other sources.

The present invention overcomes the diificulties of the known art by energizing a column of air with power waves .of superaudible frequency, and then controlling the energy of the air column in accordance with the waves of the sounds which are to be reproduced.

The production of the super-audible power air wave may be accomplished by any mechanism capable of producing a power wave which is beyond audible frequency so that no audible sound will be heard when such power air wave is unmodified. The power wave energized air is then eflectively con- :trolled so that the energy in the air column acts to produce sound waves of audible frequency. This control may be done in any way whereby the modulation of the power Wave shall correspond to the sound wave flowing through air in a normal way. v

The many objects of the present invention will be apparent from consideration of the specification and the drawings forming a part of this application, and throughout which like parts are designated by like charactors.

The drawings herewith diagrammatically illustrate certain embodiments of the invention and ways of carryingout the method comprising the best known to the inventor at the present time but the invention may be embodied in and carried out by other devices, so that the disclosure is to be understood as illustrativeand not in a limiting sense.

Fig. 1 is a diagrammatic view illustrating an electrical embodiment of the invention,

such as may be utilized with a radio receiving set.

Fig. 2 is a diagrammatic view illustrating details shown in Fig. 1.

Fig. 3 is a diagrammatic detail illustration of an adaptation of the invention to a cogstruction operable by a phonograph recor v Fig. 4 is a detail view showing one form of valve for controlling the energy of an air column. r

Fig. 5 is a detail view of a different form of valve for controlling the energy of the air column.

Fig. 6 illustrates diagrammatically another form of the invention.

Fig. 7 illustrates what is believed to be the wave resulting from the devices disclosed.

Referring now to the drawings and more specially to Figure 1, the horn 1 terminates in a throat 2 which leads to a chamber 4 that is closed upon one side by a small light diaphragm 5. The throat 2 of the horn may be slotted, as shown in Figure 5 by slots 6 and a correspondingly slotted sleeve 7 may be mounted to oscillate around the throat 2. The sleeve 7 may be connected with a link 8 to a suitable electromagnetic device 9 that is connected to the ordinary radio receiving set 10. The diaphragm 5 is similarly connected with the electromagnetic energizer 11 that is connected with an oscillator 12. The oscillator 12 operates to cause the diaphragm 5 to vibrate at super-audible frequency. This, therefore, sets up in the horn super-audibl air waves which are to a certain extent ciggfentrated in the throat of the horn because the small diameter of the air column at this point. The sleeve 7 being connected with the electromagnetic devices 9 connected to the radio set, will oscillate in accordance with electrical impulses flowing from the radio set. Since these 'impulses correspond to the tone wave being sent out at a broadcasting station with which the radio set 10 is in tune, the slotted sleeve 7 will in turn be oscillated in accordance with these tone waves. sleeve 7 correspond with the slots 6 in the As the slots in the is transmitted to the main column of air in the horn 1. It therefore will be seen that since the slotted sleeve 7 operates to open and close the slots 6 in the throat 2 in accordance with the variations in tone waves, the energy in the column of air in the horn 1 will be modulated in accordance with the sound waves that correspond to the electrical waves delivered through the radio set, and audible sound Waves will be emitted from the horn.

Referring now to Figures. 3 and 4, the control for the super-audible power wave comprises a'grid' valve formed of a slotted stationary member 14 and a similarly slotted movable member 15. As illustrated in F igure 3, the movable member 15 of the grid valve may be oscillated by the tone grooves 16 in a rotating phonograph record 17 since the tone grooves communicate an oscillating motion to the needle bar 18, which in turn is connected with the movable member 15 to slide the same back and forth, thereby bringing the slots in the members 14 and 15 into and out "of register, opening and closing the grid valve. Where desired, the neutral or central position of the needle bar and likewise the movable member 15 of the gird valve may be adjusted, by means of thumb screws 20 and 21 which are adapted to compress springs 22 and 24 on opposite sides of a projection 25 carried by the connection 26 through the needle bar between the needle bar 18 and the movable member 15 of the grid valve. In the construction illustrated in Figure 3, it is preferable that the throat 27 of the horn at its smallest diameter shall not be greater than the sum of the area of the slots in the grid valve when the movable member 15 is positioned to fully open the slots of the valve. This relation of area insures that the full eifective super-audible waves produced by the diaphragm will be transmittedvthrough the throat of the horn 27 when the grid valve is fully open.

Fig. 6 discloses another device for carrying out the invention and comprises an amplifying horn 1 with which is associated a diaphragm 28 preferably made of alumimum and having thin edges 29 and a relaaudible rate to set up super-audible air waves in the horn.

In the form illustrated in Fig. 6, the arrangement is such that the power (in this case the electricalcurrent to the horn magnet) which produces the super-audible air waves, is varied at audible frequency to vary the super-audible air impulses at an audible rate to produce the desired sound.

It is to be understood that valves (such for example as those illustrated in Figs. 1 and 3) might be used in connection'with the device shown in Fig. 6, in which case the control (such as the radio receiving set) is connected to operate the valve and the oscillator operates the diaphragm at substantially constant amplitudes. It is also to be understood that the phonograph record 17 may operate to vary the super-audible frequency current and produce variation in the diaphragm operation to produce the audible sounds without the use of the valve mechanism.

Since the present invention contemplates the production of super-audible air impulses with the peaks thereof varied at audible rates to produce sound, it follows that the mechanical defects of the impulse producing devices (for example the diaphragms here illustrated) will go into the super-audible range and will not distort the sound wave. The record scratch of the phonograph needle being a mechanical vibration Will not be transmitted into the sound wave. Fig. 7 illustrates what is believed to be the sound wave produced by this method and wherein the peaks 35 of the super-audible impulses 36 form audible air waves.

In the several forms of the invention here disclosed, it is desirable that the super-audible rate of air pulsations shall be safely above audible range and yet be as low as is consistent with constant inaudibility. Where the device is used with a radio, the oscillator may be fed with current from a detector or the desired oscillation frequency may be obtained by the well known hetrodyne orbeat system which is well known in 1 I the radio art.

Having described my invention, what I claim is:

1. A device for producing sound .compris ing means for producing super-audible air pulsations, and means operable upon said air pulsations to control said pulsations at an audible rate to produce audible sound waves.

2. A device for producing sound comprising'means to form a column of air, means for producing super-audible air pulsations in said column of air, and means operable upon said air pulsations to control said pulsations at an audible rate to produce audible sound waves in said column of air.

3. A device for reproducing sound comprising, an amplifying horn, a vibrating element associated with said horn, means to vibrate said element at a super-audible rate to produce super-audible air waves in said horn, and means operable upon said su eraudible air waves to control same to pro uce audible air waves in said horn.

4. A device for reproducing sound comprising, an amplifying horn, a vibrating diaphragm associated with said horn, means to vibrate said diaphragm at a super-audible rate to produce super-audible air waves in said horn, and valve means operable upon said super-audible a'ir waves to control same to produce audible air waves in said horn.

5. A device of the class described comprising an amplifying born, a diaphragm forming a wall of a chamber connected with said horn, electrical means to super-audibly vibrate said diaphragm to produce superaudible pulsations in the air in. said horn, and means to control said pulsations at audible rates to produce sound waves.

6. A device for the production of sound comprising means for producing super-audible air pulsations, and means eflective after said pulsations have been produced to control said pulsations at an audible rate to establish audible sound waves.

7. A device for producing sound comprisingan amplifying horn, a chamber connect,- ed with said horn, means to produce superaudible air pulsations in said chamber, and

means to cause said pulsations to set up sound waves in said horn- 8. The method of producing sound waves comprising producing su er-audible air waves of substantially uniorm amplitude and then varying said amplitude at an audible rate. c

' 9. The method of producing sound comprising producin super-audible air pulsations, and contro ing the pulsations at audible frequency to produce sound.

10. The method of producing sound com! prising energizing a column of air by setting up therein super-audible pulsations and controlling the energy in the air column to produce audible air waves.

11. The method of producin sound that comprises producing super-audi 1e air ulsations, and varying the production 0 said pulsations at an audible rate.

12. The method of producing sound that comprises producing super-audible air pulsations in a column of air, and varying the amplitude of such pulsations to set up audible sound waves in said column of air.

13. The method of reproducing sound which comprises vibrating an air column at a super-audible rate, and modulating the super-audible vibration by audible frequency changes in the amplitude of the superaudible vibration.

14:. A device for producing sound comprising means for producing continuous super-audible air pulsations, and means to vary the amplitude of said pulsations at an audlble rate to produce audible sound waves.

GEORGE RAMSEY. 

